Relaxation Dynamics of Anisotropic Shaped CdS Nanoparticles

Here, we report the influence of shape of nanocrystals (NCs) on the carrier relaxation dynamics of photoexcited CdS NCs using time-resolved spectroscopy. The decay curves have been analyzed using stretched-exponential function and the average decay time and the stretching exponent beta are found to be changed with varying the shape of CdS NCs. A stochastic model of carrier relaxation dynamics of CdS NCs has been proposed to estimate the values of the radiative recombination rate, the average number of surface trap states, the luminescence quenching rate due to surface trap states and the rate due to nonradiative recombination from trap state to ground state. Analysis suggests that surface curvature plays an important role in the relaxation dynamics, and it is found that the number of surface trap states in CdS nanospheres is lower than that of CdS nanorods/triangles.